File storage cabinets are used for filing documents and are generally of the vertical and lateral type. Such file cabinets usually include a number of file drawers vertically stacked with each file drawer being movable from within the cabinet housing to an extended open position to provide access to the drawer space. In a vertical file cabinet the length of the file drawer extends out of the file cabinet housing with the files extending across the drawer, whereas in a lateral file drawer the length of the drawer extends across the cabinet housing so that when the drawer is opened it is moved transverse to its length.
It very frequently occurs that if more than one drawer is moved to the open position at the same time, the file cabinet assembly has a tendency to tip forward in the opening direction of the drawers. In other words, the center of gravity of the cabinet is shifted sufficiently forward that the entire assembly becomes unstable and can dangerously fall forward, sometimes causing injury to a party standing in front of the cabinet.
Hundreds of mechanisms have been developed to overcome this tipping problem by preventing more than one drawer from being opened at the same time. Many of these systems include mechanisms disposed along one side of the drawers for being moved to a locking position in response to opening movement of one of the drawers.
U.S. Pat. No. 3,454,320 to Olree discloses a system having a rod with a radially extending actuating arm associated with each drawer for rotating the rod upon opening movement of the drawer to rotate a second locking arm associated therewith into interfering position with each of the other drawers. A major deficiency in this system is that it allows two drawers to rotate the rod simultaneously during opening movement of both drawers.
The U.S. Pat. No. 3,883,199 to Cawley, Jr. et al. discloses yet another system utilizing a rotating rod with arms that coact with the drawers for rotating the rod to a locking position upon opening of one of the drawers. The mechanism incorporates a security locking system whereby the rod may be moved vertically for preventing opening of all of the drawers. It, however, has the similar deficiency of allowing two drawers to be opened simultaneously.
There are also systems including vertically stacked elements, one or more of which are vertically movable to drawer-locking positions in response to opening movement of one of the drawers. Exemplary of such a system is that shown in U.S. Pat. No. 4,480,883 to Young wherein the stack of elements includes a cam associated with each drawer opening for rotation about a horizontal axis in response to opening movement of the associated drawer to vertically move the other elements in the stack to prevent any of the other cams from rotating, thereby blocking the opening movement of the other drawers. In this system the contacting surfaces between the cam and the drawer are the same for rotating the cam during opening movement of the drawer as for preventing the drawer from being opened by the cam when the cam is prevented from rotating because of another cam in the system having been rotated as a result of another drawer being opened. In other words, the actuating surfaces between the cam and the drawer are the same as the locking surfaces between the mechanism and the drawer.